This invention relates to a double orbital transmission and, in particular to an improvement or modification to the transmission disclosed in our earlier International Patent Application No. PCT/AU94/00445 (publication No. WO-95/06829). The contents of the earlier application are incorporated into this specification by this reference.
As is disclosed in the above international application, infinitely variable transmissions which operate on a friction principle are well known. One such transmission comprises a vee-belt and pulley system. The pulleys are each split into two frusto-conical portions which are movable axially towards or away from each other so as to vary the effective pulley diameter at which the belt contacts the puller. The major problem with this and other friction transmissions is that they are unable to transmit high torques, at least without making a transmission of excessive size as to be impractical.
A requirement accordingly exists for a variable ratio transmission which is able to transmit high torques in a practical manner. Transmission systems capable of coping with large torque loads in relatively small units, are inevitably based on rigid body elements such as gears formed in metals. This poses great problems for infinitely variable transmissions.
There is disclosed in my patent application No. PCT/AU81/00146 an infinitely variable mechanical transmission. Basically, this mechanism comprises means for transforming a circular input motion into non-circular periodic motion of a plurality of elements, or iterated operations of a single element, utilising only a part of the periodic motion of each element and transforming this part back into a rotary output motion. These parts of the periodic motion of the plurality of elements are connected or xe2x80x9cassembledxe2x80x9d sequentially to provide the output motion. This process is what is termed xe2x80x9cmotion transformationxe2x80x9d and results in so-called xe2x80x9ctorque conversionxe2x80x9d.
In the transmission disclosed in International Patent Application No. PCT/AU81/00146, rotary motion of an input shaft is converted by an eccentric of variable eccentricity into a periodic motion of a plurality of racks. The periodic motion of each rack is converted into a rotary periodic motion of a pinion, and a selected part of the motion of the pinion is applied to a separate satellite gear of a planetary gear arrangement. The resultant output motion of a sun gear of the planetary gear arrangement is effected by the sequential action of each satellite gear. More specifically each rack operates in sequence to apply part of its motion to is associated satellite gear and thus to the output sun gear, a switching device being incorporated in the mechanism to switch on and off an operative connection between a pinion gear which is continually driven by the rack, and the associated satellite gear. While it may be theoretically possible to achieve either instantaneous switching or precise synchronism between the switching off of the operative connection between one rack and its associated satellite gear and the switching on of the operative connection between the next rack in the sequence and its associated satellite gear, it is not possible in practice to achieve this, and as a result the output will not be completely smooth; this may manifest itself as a slight jerkiness which can be felt it the output while under load. Whereas for some uses this lack of smoothness may be tolerated, for many uses it is necessary to obtain a flat or smooth and continuous output.
Thus, attempts to produce rigid body continuous variable transmissions have been based on the production of a plurality of partial intermediate circular or non-circular motions produced by a circular input and at some stage transformed back to a collated circular motion.
Pires U.S. Pat. No. 4,983,151 issued Jan. 8, 1991 discloses a mechanism which attempts to provide a smooth output by what Pires terms xe2x80x9caveraging intermediate rotationsxe2x80x9d. The device disclosed in Pires requires considerable precision and whilst the output is smoother than the transmission referred to in PCT/AU81/00146, the output still is no sufficiently smooth for many applications.
Our earlier International Patent Application No. PCT/AU94/00445 discloses the use of load distributing means for differentially distributing the load taken by secondary members of the transmission so that the load is distributed between at least two such members at any one time. Because of this distribution of load, the output power provided by the secondary members is smoother and continuous rather than jerky and discontinuous and therefore the transmission of input power to output power is smoother than in prior art rigid body continuously variable transmissions. The load distributing means which differentially distributes the load, collapses the kinetic form of the overlapping partial circular or non-circular motions and serially links their associated load functions by differentially distributing the load between at least two of the secondary members.
The specific embodiments disclosed in International Patent Application No. PCT/AU94/00445 are directed to bicycle transmissions, winches and other generally slow moving mechanisms although the invention is applicable to any type of transmission which requires or could use continuous variation in the drive output between a minimum drive ratio and a maximum drive ratio.
The present invention stems from further development of the invention disclosed in International Patent Application No. PCT/AU94/00445 and which, whilst could be used in any application requiring or desiring continuously variable transmission from a minimum ratio to a maximum ratio, is more concerned with higher speed and higher power applications such as heavy duty winch applications and automotive applications.
The invention may be said to reside in a transmission including:
an input means;
an output means;
a plurality of secondary members for supplying output power for only part of each rotary cycle of the input means;
power transfer means for engagement with the plurality of secondary members;
the plurality of secondary members being coupled to one of the input means or the output means and the power transfer means being coupled to the other of the input means or the output means;
first orbital means for causing the plurality of secondary members to undergo orbital motion; and
second orbital means for causing the power transfer means to undergo orbital motion so the combined orbital motions cause power to be transmitted from the input power supply to the output power supply.
Preferably the transmission further includes load distributing means for differentially distributing the load taken by the secondary members between at least two of the secondary members at any one time.
Preferably the transmission includes phase changing means for changing the phase relationship of the orbital motions to, in turn, change the drive ratio of the transmissions.
Preferably the orbital motion is a stationary orbital motion but in other embodiments the orbital motion could be either a progressive or a regressive orbital motion.
Preferably the secondary members comprise a first set of pawls and a second set of pawls.
Preferably the first orbit means comprises a pawl carriage for carrying the first and second sets of pawls, the pawl carriage having an epicyclic plate, an orbital control plate adjacent the epicyclic plate and orbit control means between the orbital control plate and the epicyclic plate.
Preferably the orbit control means comprises a hole or recess on one of the orbital control plate or epicyclic plate and pins for engaging the hole or recess on the other of the orbital control plate or epicyclic plate.
In other embodiments, the orbit control means may comprise a gear recess on one of the epicyclic plate or orbit control plate and a gear member, for receipt in the gear recess, on the other of the epicyclic plate or orbit control plate; or a recessive or progressive orbital gear arrangement.
Preferably the power transfer means comprises a first assembler ring for engaging with the first set of pawls and a second assembler ring for engaging with the second set of pawls.
Preferably the first and second assembler rings have ratchet teeth on an inner peripheral surface and the pawls carry shoes which in turn have ratchet teeth for engaging with the ratchet teeth on the first and second assembler rings.
Preferably the pawl carriage has an axial portion and the pawls are pivotally coupled to the axial portion of the carriage ring.
Preferably the second orbit means comprises an orbit body for carrying the first and second assembly rings, the orbit body having an epicyclic plate, an orbital control plate adjacent the epicyclic plate and orbit control means between the orbital control plate and the epicyclic plate.
Preferably the orbit control means comprises a hole or recess on one of the orbital control plate or epicyclic plate and pins for engaging the hole or recess on the other of the orbital control plate or epicyclic plate.
In other embodiments, the orbit control means may comprise a gear recess on one of the epicyclic plate or orbit control plate and a gear member, for receipt in the gear recess, on the other of the epicyclic plate or orbit control plate; or a recessive or progressive orbital gear arrangement.
Preferably the input means comprises a first input shaft having an eccentric upon which the pawl carriage is mounted and a second input shaft having an eccentric upon which the orbit body is mounted.
Preferably the input means also includes phase control means for controlling the phase relationship between the first and second input shafts and therefore between the first and second eccentrics to in turn control the phase relationship between the first and second eccentrics and therefore the phase relationship between the orbital motions.
Preferably the differential load distribution means comprises differential load distribution gears arranged between the first and second assembler rings so that load can be transmitted from the first assembler ring to the second assembler ring and vice verse to thereby differentially distribute load between one of the first set of pawls and one of the second set of pawls at any one time.
Preferably the engagement shoes are guided in a guide ring arranged between the first and second assembler rings.
Preferably the engagement shoes have guide flanges which are received in grooves in the guide ring to thereby guide movement of the engagement shoes relative to the guide ring and the first and second assembler rings.
Preferably the differential load distribution gears are mounted on the guide ring and engage bevel teeth on side surfaces of the first and second assembler rings.
In this embodiment of the invention, the pawls are mounted on the pawl carriage which is in turn arranged on the first eccentric and the assembler rings are arranged radially outwardly with respect to the pawls.
In one embodiment of the invention, the teeth on the assembler rings which engage with the teeth on the engagement shoes are ratchet teeth.
In another embodimelt of the invention, positive engagement means is provided for moving the pawls into a position where the two orbits are able to positively cause engagement between the pawls and the assembler rings for any given phase relationship between the orbits. In this embodiment, the teeth on the assembler rings which are to engage the pawls are of sinusoidal shape. In this embodiment of the invention, the pawls may be provided with teeth at their ends rather than engagement shoes and preferably the teeth are also of sinusoidal shape. However, the pawls could be provided with engagement shoes having teeth of sinusoidal shape.
In this embodiment of the invention, the assembler rings are mounted on the first eccentric and the pawls are arranged radially outwardly of the assembler rings for engagement with the assembler rings.
Preferably the positive engagement means comprises arm members on the pawls and a control body for axial movement relative to the pawls, the control body having wedge-shaped recesses for receiving the arms so that upon axial movement of the control body, the wedge-shaped recesses contact the arms to move the pawl bodies radially to thereby cause positive engagement of the pawls with the assembler rings.
In this embodiment, the pawls are supported by the orbit body and the orbit body is provided with openings for receiving the pawls.
Preferably control means is provided for axially moving the control body to engage and disengage the pawls with respect to the assembler rings.
In a further embodiment of the invention, the first orbital means includes a first eccentric and orbit control means for controlling the orbital motion and the second orbital means comprises a plurality of axles from which is mounted the power transfer means, the axles having eccentrics and being rotatable to provide controlled orbital motion to cause the power transfer means to undergo orbital motion.
Preferably the power transfer means are supported by an orbital body mounted on the axles.
The present invention also provides a transmission mechanism including:
an input power supply for supplying input rotary power;
an output power supply for providing rotary output power;
a plurality of secondary members arranged between the input power supply means and the output power supply means for transmitting power from the input power supply means to the output power supply means, the plurality of secondary members comprising at least a first array, including at least one secondary member, between the input power supply and the output power supply, and a second array including at least one further secondary member between the input power supply and the output power supply, the first and second arrays being in parallel with respect to one another;
a first assembler ring for engagement with the first array of secondary members;
a second assembler ring for engagement with the second array of further secondary members;
the secondary members of the first array and the secondary members of the second array being in engagement with the respective first and second assembler rings through only part of each rotary cycle of the transmission mechanism; and
a load a distributing gear engaged between the first and second assembler rings for differentially distributing the load taken by the secondary members between the said at least one secondary member of the first array and the at least one further secondary member of the secondary array.
Preferably the first and second assembler rings have gear teeth on radially extending side surface thereof for engagement with the load distribution gear.
In one embodiment of the invention, the secondary members are arranged radially inwardly of the first and second assembler rings and ratchet gear teeth are provided on an inner peripheral circumference of the first and second assembler rings for engagement with the respective first array of secondary members and second array of secondary members.
In another embodiment, the first and second assembler rings are arranged radially inwardly of the secondary members and ratchet gear teeth are provided on an outer circumferential surface of the first and second assembler rings for engagement respectively with the first array of secondary members and second array of secondary members.
In another embodiment of the invention, the transmission is adapted to provide output rotation in a clockwise or anticlockwise direction so that drive in a first direction can be provided or drive in an opposite direction can be provided.
In this embodiment of the invention, the transmission mechanism include
a second plurality of secondary members for supplying output power for only part of each rotary cycle of the input means;
a second transfer means for engagement with the plurality of secondary members;
the second plurality of secondary members being coupled with the plurality of secondary members for movement with the plurality of secondary members and the second transfer means being integral with or coupled to the power transfer means; and
the plurality of secondary members and power transfer means engaging and providing drive during rotation in a first direction of the input means and the second plurality of secondary members and second power transfer means engaging and providing drive during rotation in an opposite direction of the input means.
Preferably the transmission includes first plurality of secondary means are constrained so as to only engage the transfer means in the region when the transfer means and secondary members are closest during orbital movement of the secondary members and transfer means.
Preferably the double orbiting system produced by the first orbital means and second orbital means provides two drive phases, one on the closest approach side of the orbiting power transfer means to the orbiting plurality of secondary a members to produce a primary orbit and one on the opposite side to produce a counter phase orbit.
Preferably the transmission includes means for switching off one of the phases of the transmission to enable drive to be transmitted either direction so that as the second plurality of secondary members begins to transmit drive, there is no destructive interference from the plurality of secondary members as one engages the primary phase and the other engages the counter phase.
The invention may also be said to reside in a transmission including:
an input means;
an output means;
a first plurality of secondary members for supplying output power for only part of each rotary cycle of the input means a first direction;
a second plurality of secondary members for supplying output poser for only part of each rotary cycle of the input means in a reverse direction opposite the first direction;
power transfer means for engagement with the first plurality of secondary members and the second plurality of secondary members;
first orbit control means for causing the first and second plurality of secondary members to undergo orbital motion;
second orbital control means for causing the power transfer means to undergo orbital motion so the combined orbital motion causes power to be transmitted from the input power supply to the output power supply; and
means for selectively allowing supply of power between the first plurality of secondary members and the power transfer means in the first direction and supply of power between the second plurality of secondary members and the power transfer means in the reverse opposite direction so the transmission can selectively supply power in the first direction or the opposite reverse direction.
Preferably the direction control means comprises a switch having an activation point and a first engagement tooth and a second engagement tooth, the switch being pivotally mounted to the first orbital means;
the first and second plurality of secondary members including first and second respective carriers, the first and second respective carriers having teeth for engagement selectively with the first or second tooth of the switch; and
upon rotation of the input means in the first direction, the teeth of the carriage carrying the first plurality of secondary members engage the activation point of the switch to pivot the switch to cause the first tooth to engage with the teeth of the carriage so as to lock the first carriage to the first orbit control means; and
upon rotation of the input means in the reverse opposite direction the teeth of the second carriage engage the activation point to pivot the switch to cause the second tooth to engage with the teeth of the second carriage to lock the second carriage to the first orbital means.
Preferably the first orbital means comprises a orbit control cylinder coupled with the output means.
Preferably the orbit control cylinder is mounted on a first eccentric which in turn is mounted on the input shaft.
Preferably the plurality of first secondary members comprises two sets of pawls.
Preferably the second plurality of secondary members comprises two set of pawls.
Preferably the power transfer means comprises first and second pairs of assembler rings, each pair of assembler rings having a differential load distribution gear arranged therebetween for differentially distributing load between a pawl in the first set of pawls and the second set of pawls of each of the first plurality of secondary members and second plurality of secondary members.
Preferably the second orbit means comprises an orbit body carrying the first and second assembler rings.
Preferably the differential load distribution gears are coupled to the orbit body.